Lou33, we're just like you: a joint address and two separate ones, but we keep up with each others separate accounts (his is more interesting than mine, so I check his more regularly, although he uses mine for other stuff sometimes). The only time we don't check is when there's an explicit "I have bought you a present and you must not check my account" type thing.
We do have separate log-ins to the computer, though. His bookmarks don't mesh that well with mine. Plus, I like my background and interface much better. (We know each others' passwords, though.)